efforts, curtailment of fertility may occur in an inefficient and inhumane manner, as shown by the prevalence of abortion performed without medical assistance in many parts of the world today, with consequent maternal morbidity and mortality.*
As with most equilibrium economic models, a change in the rate of growth of one variable has its greatest effect in the short run, whereas after other factors have fully adjusted to the new growth rate, the long-run equilibrium effects on the system are more moderate. In a sense, the family, which was subjected to changing demographic and economic pressures in the postwar period, is adjusting to bring its behavior into equilibrium with the opportunities and constraints of its new environment. In this case the lag in behavioral adjustment has been 2 decades, the time it takes to form a complete family. During this period the transitory pressures are acute and have their most marked effect on household welfare and resource allocation; they generate pressing demands for public sector services as well. But what are the transitory effects of a trend toward long-term family-demographic and -economic equilibrium?
To recapitulate, the postwar decline in death rates creates a transitory burden of children for adult society to rear, train, and equip for modern employment. However, any reduction in fertility that follows will permit a comparable reduction in dependency burden with the associated social opportunities to educate and train the younger generation more adequately and to invest a sufficient amount to employ a larger proportion of it in modern high productivity and high-wage sectors of the economy. From the family's perspective, the population explosion is largely a transitory burden carried by the current generation, a challenge to today's family planning policymakers, and perhaps a promise of future development opportunities if the challenge is met and discharged effectively. Having exchanged one perspective for another, however, one should not overlook the broader outlines of the population problem; though its roots are in the family, the repercussions of the problem do not necessarily stop there.
QUALIFICATIONS AND SUMMARY
For analytic purposes, the postwar increase in population growth rates in low income countries can be divided into two components: that part due to the reduction in child death rates and that part due to the reduction in adult death rates.' The first component is directly responsible for increases in the
*See Abdel R. Omran, "Abortion in the Demographic Transition," in this volume.
'The distinction here is between the reduction in the death rate of children whose parents arc still fecund and the reduction in death rates to other persons, mainly adults. About half of the lives saved by the postwar decline in mortality are less than 20 years of
iar> (\icina ctnnHnrrl Hnecr>o r\f 1iFr> toKlrxA TVin t->rr>^ifo fi-o^ti^-vn r\f tlir. ii-i^ro.ior. in oimriirinnudy using multivariatc nonlinear regression analysis allied with a behavioral model of fertility as discussed in this paper see (3).